1. Field of the Invention
The present invention relates to a device for changing over an air passage by moving a film screen. The device is adequately applicable to an automotive air-conditioner.
2. Description of Related Art
An example of a conventional film screen for use in controlling an air passage is disclosed in JP-A-5-201234. The film screen is formed by alternately laminating resin film layers and cloth layers, or by laminating a resin layer and a cloth layer. In this manner, the film screen strength in both tensile and bending force is secured. The film screen thus formed is disposed in the air passage, forming a curved or serpentine path. In the conventional device, a side of the curved or serpentine path at which the cloth layer or the resin layer is positioned is not considered. In other words, the cloth layer or the resin layer forming the film screen is arbitrarily positioned at a convex side or a concave side of the curved or serpentine path.
A film screen formed by laminating a resin film layer and a woven fabric layer has been actually tested in an automotive air-conditioner. It has been found out through the test that part of the film screen wound around a roller is deformed by heat to a shape of the roller and that the deformed part does not easily recover its original shape. This deformation is referred to as a “transferred deformation” because the shape of the roller engaging with the film screen is transferred to the film screen. The transferred deformation formed on the film screen prevents good sealing between an air-conditioner casing and the film screen. The transferred deformation generates an air leakage and vibrating noise.